Concentrating Solar Photovoltaic-Thermal System

Abstract

Systems, methods, and apparatus by which solar energy may be collected to provide heat, electricity, or a combination of heat and electricity are disclosed herein.

1 . A method for collecting solar energy, the method comprising:
 concentrating solar radiation onto a solar energy receiver comprising solar cells that convert at least some of the solar radiation to electricity;   flowing a heat transfer fluid through the receiver to collect heat from the solar cells; and   controlling a flow rate, an initial temperature, or a flow rate and an initial temperature of the heat transfer fluid to maximize a total value of electrical power output and heat collected from the solar cells.   
     
     
         2 . The method of  claim 1 , comprising reducing a flow rate or increasing an initial temperature of the heat transfer fluid to increase the value of the collected heat. 
     
     
         3 . The method of  claim 1 , comprising increasing a flow rate or decreasing an initial temperature of the heat transfer fluid, to increase the electric power output. 
     
     
         4 . The method of  claim 1 , wherein the flow rate, the initial temperature, or both the flow rate and the initial temperature of the heat transfer fluid are adjusted in response to a signal from a purchaser of the electric power output. 
     
     
         5 . The method of  claim 1 , wherein the flow rate, the initial temperature, or both the flow rate and the initial temperature of the heat transfer fluid are adjusted in response to a change in the value of the electric power output. 
     
     
         6 . The method of  claim 1 , wherein the flow rate, the initial temperature, or both the flow rate and the initial temperature of the heat transfer fluid are adjusted in response to a signal from a purchaser of the heat. 
     
     
         7 . The method of  claim 1 , wherein the flow rate, the initial temperature, or both the flow rate and the initial temperature of the heat transfer fluid are adjusted in response to a change in the value of the heat. 
     
     
         8 . The method of  claim 1 , wherein the flow rate, the initial temperature, or both the flow rate and the initial temperature of the heat transfer fluid are adjusted at least daily to maximize a total value of the electrical output and heat collected. 
     
     
         9 . The method of  claim 8 , wherein the flow rate, the initial temperature, or both the flow rate and the initial temperature of the heat transfer fluid are adjusted at least hourly to maximize a total value of the electrical output and heat collected. 
     
     
         10 . The method of  claim 1 , comprising, after collecting heat from the solar cells with the heat transfer fluid, further heating the heat transfer fluid with additional solar radiation without producing electricity from the additional solar radiation. 
     
     
         11 . The method of  claim 1  comprising controlling the flow rate of the heat transfer fluid through the receiver such that the heat transfer fluid is heated during a single pass through the receiver to a desired operating temperature for a thermal application. 
     
     
         12 . The method of  claim 1 , comprising cooling heat transfer fluid, storing the cooled heat transfer fluid, and using the cooled heat transfer fluid to collect heat from the solar cells at a time when doing so increases the total value of electrical power output and heat collected from the solar cells. 
     
     
         13 . The method of  claim 12 , comprising dispatching the cooled heat transfer fluid to the receiver in response to a signal from a purchaser of the electric power requesting additional electric power. 
     
     
         14 . The method of  claim 12 , comprising dispatching the cooled heat transfer fluid to the receiver in response to an increase in the value of the electric power output. 
     
     
         15 . A method for collecting solar energy, the method comprising:
 cooling a heat transfer fluid to below a first temperature and storing the cooled heat transfer fluid;   concentrating solar radiation onto a solar energy receiver comprising solar cells that convert at least some of the solar radiation to electricity;   introducing a heat transfer fluid at a second temperature, greater than the first temperature, into the receiver and flowing it through the receiver to collect heat from the solar cells to exit the receiver at a third temperature greater than the second temperature;   dispatching stored heat transfer fluid at the first temperature to the receiver to decrease the temperature of the solar cells to below the second temperature and thereby boost their electrical power output.   
     
     
         16 . The method of  claim 15 , comprising dispatching the stored heat transfer fluid at the first temperature to the receiver in response to a signal from a purchaser of the electric power output. 
     
     
         17 . The method of  claim 15 , comprising dispatching the stored heat transfer fluid at the first temperature to the receiver in response to a change in the value of the electric power output. 
     
     
         18 . The method of  claim 15 , wherein the first temperature is less than about 15° C. 
     
     
         19 . The method of  claim 18 , wherein the second temperature is greater than about 65° C. 
     
     
         20 . The method of  claim 15 , wherein the first temperature is less than about 10° C. 
     
     
         21 . The method of  claim 15 , comprising transferring heat in the heat transfer fluid at the third temperature to a thermal application, and ceasing heat transfer to the thermal application upon dispatch to the receiver of heat transfer fluid at the first temperature. 
     
     
         22 . The method of  claim 21 , wherein the first temperature is less than about 15° C. and the second temperature is greater than about 65° C. 
     
     
         23 . The method of  claim 15 , comprising heating the heat transfer fluid dispatched to the receiver at the first temperature, during its passage through the receiver, to a fourth temperature, lower than the third temperature, and storing the heat transfer fluid at the third temperature. 
     
     
         24 . The method of  claim 23 , comprising further heating the heat transfer fluid stored at the third temperature to a higher temperature desired for a thermal application. 
     
     
         25 . The method of  claim 23 , comprising cooling the heat transfer fluid stored at the third temperature to a temperature less than about the first temperature, storing it, and dispatching it again to the receiver. 
     
     
         26 . A method for collecting solar energy, the method comprising:
 concentrating solar radiation onto a solar energy receiver comprising solar cells that convert at least some of the solar radiation to electricity;   flowing a heat transfer fluid through the receiver to collect heat from the solar cells; and   controlling the flow rate of the heat transfer fluid through the receiver such that the heat transfer fluid is heated during a single pass through the receiver from a first temperature on entering the receiver to a second temperature on exiting the receiver, the second temperature desired for a thermal application.   
     
     
         27 . The method of  claim 26 , wherein the second temperature is greater than about 65° C. 
     
     
         28 . The method of  claim 26 , comprising, after heating the heat transfer fluid in the receiver, storing the heat transfer fluid at about the second temperature. 
     
     
         29 . The method of  claim 28 , comprising filling an initially empty or substantially empty storage vessel with heat transfer fluid introduced into the storage vessel at about the second temperature. 
     
     
         30 . The method of  claim 26 , comprising transferring heat from the heat transfer fluid at about the second temperature to a second fluid. 
     
     
         31 . The method of  claim 30 , comprising storing the second fluid at about the second temperature. 
     
     
         32 . The method of  claim 31 , comprising filling an initially empty or substantially empty storage vessel with the second fluid introduced into the storage vessel at about the second temperature. 
     
     
         33 . The method of  claim 31 , comprising:
 introducing second fluid at about the second temperature into an upper portion of a first storage vessel;   withdrawing second fluid from a lower portion of the first storage vessel and introducing it into an upper portion of a second storage vessel;   withdrawing second fluid from a lower portion of the second storage vessel and transferring heat to it from additional heat transfer fluid at the second temperature to reheat the second fluid to about the second temperature; and   introducing the reheated second fluid to an upper portion of the first storage vessel.   
     
     
         34 . The method of  claim 33 , comprising withdrawing second fluid from an upper portion of the first storage vessel for use in a thermal application, and introducing into the lower portion of the second storage vessel second fluid returned from the thermal application. 
     
     
         35 . A solar energy collector comprising:
 a photovoltaic-thermal portion that collects concentrated solar radiation and provides an electrical power output and heats a heat exchange fluid; and   a thermal portion that collects additional concentrated solar radiation and further heats the heat exchange fluid but does not significantly contribute to the electric power output.   
     
     
         36 . The solar energy collector of  claim 35 , wherein the photovoltaic-thermal portion and the thermal portion are integral. 
     
     
         37 . The solar energy collector of  claim 35 , wherein the photovoltaic-thermal portion and the thermal portion are physically separate from each other but fluidly coupled to allow flow of the heat transfer fluid from the photovoltaic-thermal portion to the thermal portion.